Resistance element



Jan. 24, 1928. R. F. BUCHHOLZ RESISTANCE ELEMENT Filed June 24. 1924 I INVENTOI? 'mx 69m ATTORNEY Patented J 24, 1928.

UNITED STATES PATENT OFFICE. I

RENE I. BUCHHOLZ, OF PHILADELPHIA, PENNSYLVANIA, ABSIGNOB TO A'IWATEB KENT MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A 003- PORATION OF PENNSYLVANIA.

RESISTANCE ELEMENT.

Application filed June 24,

My invention relates to resistances, and more particularly to resistances utilizable in connection with audions and similar devices for affording leakage paths or for coupling the output circuit to another circuit.

In accordance with my' invention the resistance material comprises lead oxide, preferably litharge, and glycerine or equivalent, formmg) therewith a solid having the property of inding or cementing; and more particularly my resistance material comprises a mixture of litharge with lamp black or equivalent finely divided conducting material, and glycerineor equivalent.

For an understanding and illustration of my invention reference is to be had to the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a resistance unit in accordance with my invention.

Fig. 2 is a diagrammatic view illustrating one of the various uses of my resistance unit.

Referrin to Fig. 1 there is shown disposed withm the bore of the tube 1, of glass or other suitable material, a mass 2 of resistance material whose ends are continuous with or homogeneously united with masses 3 of the same or other suitable material disposed within the cap or ferrule members 4 :0 of brass or other suitable conducting material suitably-secured or cemented to the tube 1 by material 5 which may be the same as the material 2 or 3, or may be any other suitable material, the masses 3 effecting elecas trical connection between the mass 2 and the ferrules 4, and the material 5 serving not only as a cement but serving also when of suitable composition to make further electrical connection with the ferrules 4.

4B The material 2 comprises leadoxide, preferably litharge, mixed in suitable proportion with glycerine, as in forming the well known lithrage hinder or cement. This material when solidfied or hardened, either by as application of suitable elevated temperature for suitable time or when subjected to ordinary atmo heric tem erature for a longer time, has a igh eci c resistance, as of the order of 6 mego s per centimeter cube.

I0 This material may be disposed ina mass 0 such length and cross section as to effect a 1924. Serial No. 721,964.

smaller masses of dimensions suitable for the formation of a resistance unit which will fit )definitely dimensioned terminal structures or mountings, especially those commonly usedin connection with audionpr.

like tubes. I I

For this purpose there is admixed with the lead oxide, preferably litharge, and preferably before application of the gl 0- erine or equivalent, lamp black or suitably finely divided graphite, carbon, metal or other conducting material. There may be added to 300 grams of pulverized litharge 1.2 grams of lamp black and after thorough mixture there are admixed 2 fluid ounces of glycerine or equivalent.

A mixture of this character when hardened or solidified will have a specific resistance of the order of .8 to 1 megohm per centimeter cube. The mass 2, Fig. 1 of this composition having a diameter of of an inch and a length of 1 inches will have a resistance of the order of 3 megohms.

, When a similar mixture comprises about 300 grams of litharge to 1.7 grams of lamp black, with admixture of about 2 fluid ounces of glycerine or equivalent, it will have after baking or hardening a resistance of about 1% megohms when of the aforesaid dimensions, namely 5 g of an inch diameter and a length of 11 inches; and has a specific resisltance of about .3 megohm per centimeter cu e.

A mixture of 300 grams of litharge and of a gram of lamp black and about 2 fluid ounces of glycerine will effect a unit of the aforesaid dimensions having a resistance of abount 4 megohms; the Specific resistance of this mixture is about 1.2 megohms per centimeter cube.

And so on, various other resistances-may be obtained by suitably proportioning the f lamp black to litharge.

In general I prefer to use a mixture of the character described having a specific resistance ranging from about .1 to about 2 megohms per centimeter cube. It will .be understood that with respect to other aspects of my invention any suitable specific resistance is comprehended.

After the preparation of the mixture of litharge, lampblack or equivalent and glycerine or equivalent it is disposed in suitable form or shape and then hardened as by subjection to ordinary atmospheric temperature for a period of about twenty-four hours or gy baking at about 200 F. for about one our.

The units of the character shown in Fig. 1 may be formed by cutting a tube into suitably short lengths to form the tube 1 of Fig. 1 and the material then introduced in the plastic state, and while still plastic the ferrules 4 are applied, suitable amounts of the same mixture, or any equivalent or suitable material, having been first introduced into the ferrules to make intimate contact or become continuous with the material 2 and to afford the masses 5- for holding the ferrules on the tube 1. The material 5 is preferably of a cementitious character and for this purpose may be of the same composition as the mass 2.

After so introducing the lastic material and applying the ferrule, t e structure is subjected to atmospheric or higher temperatures for the times above indicated whereupon the material solidifies or hardens, without material or substantial adhesion to the glass tube 1, but cementing or adhering or binding to the metal ferrules 4.

A preferred method of introduction is to force the plastic material 2 under pressure into a long glass or similar tube, and while the material therein is still plastic cutting it into suitable lengths, such as the lengths 1, Fig. 1, and then there is applied to each such length the ferrules 4 or equivalent terminals, as above described, and the baking or hardening is thereafter effected.

The resistance material of the character described has the advantage that different resistance units will correspond suitably closely in resistance. Furthermore this material utilized as a grid leak or in similar relation is noiseless, in the sense that there do not occur therewith the audion or tube noises commonly experienced with grid leaks comprising pencil marks, graphitized paper and the like.

The composition described furthermore is of a character which does not absorb moisture to substantial degree and at any rate does not absorb moisture suificient to materially alter its resistance or to affect its behavior in use, and it is therefore indifferent to changes of humidity and similar atmospheric conditions.

The composition, structure and method described lend themselves to cheap and rapid production of resistance units. The litharge and lamp black or equivalent are intimately and thoroughly mixed by mixing machinery and then after admixture with suitable amount of glycerine or equivalent, isforced as described, into long glass or similar tubes which are then cut into desired lengths while the composition or mixture is plastic and the ferrules or terminals then applied to individual lengths.

Referring to Fig. 2 there is shown a typical radio receiving apparatus comprising an audion or similar thermionic vacuum tube V utilized as a detectorr- The tube comprises an anode a, grid 9 and filament or cathode f. In circuit with the grid is the usual grid condenser Kin shunt to which is connected the grid leak resistance unit of the character described. As indicated the ferrules 4. are received in and connect with the terminal supports or mountings 6, 6, which are connected to opposite sides 'of the condenser K. In the anode circuit is the usual battery B and telephone or equivalent device T. The grid circuit contains as usual the tuning condenser C in shunt to the secondary S coupled to the primary P connected with the condenser 0 between the antenna A and earth E.

It will be understood that a resistance unit of the character described may also be connected directly from the grid 9 to the filament f, or may be connected between any two electrodes of an audion or similar vacuum tube. It may also be used in the anode circuit of an audion to efiect a coupling with another circuit, which may be for example the grid circuit of a second stage tube.

In a material of the character hereinbefore describe the litharge and glycerine apparently re-act upon each other chemically to produce among other things organic compounds of lead, the product having cementlike characteristics which are of advantage in effecting good and permanent electrical connection between the resistance material and a terminal.

What I claim is 1. An electrical resistance comprising finely divided carbon distributed through a product of mixture of lead oxide with glycerine.

2. An electrical resistance comprising finely divided carbon distributed through a product of mixture of litharge and glyc erine.

3. An electrical resistance comprising lamp black distributed through a product of mixture of lead oxide with glycerine.

4. An electrical resistance comprising lamp black distributed through a product of mixture of litharge and glycerine.

5. A resistance material com rising finely divided conducting material distributed throu h the product of mixture of litharge and g ycerine, the proportions to each other of the finely divided conducting material and litharge being such as to eifect-a spe- 5 cific resistance from about .1 to about 2 megohms per centimeter cube.

6. A resistance material comprising lamp black distributed through a product of mix ture of litharge with glycerlne, the proportions to each other of lamp black and litharge being such as to efiect a specific resistance of from about .1 to about 2 megohms per centimeter cube.

RENE F. BUCHHOLZ. 

